How to filter textbox input to numeric only?

Question

How do I suppress all data except numeric?

This is not working on KeyDown():

If e.KeyData < Keys.D0 Or e.KeyData > Keys.D9 Then
          


        

Answer 1

You can check Char.IsDigit(e.KeyChar), but the best thing to do in this case is to create a subclass of TextBox and override IsInputChar(). That way you have a reusable TextBox control that you can drop anywhere so you don't have to re-implement the logic.

(My VB is a bit rusty...)

Public Class NumericTextBox : Inherits TextBox

    Protected Overrides Function IsInputChar(Byval charCode As Char) As Boolean
        If (Char.IsControl(charCode) Or Char.IsDigit(charCode)) Then
            Return MyBase.IsInputChar(charCode)
        Else
            Return False
        End If
    End Function

End Class